DNS Updater

A lightweight, efficient, and reliable dynamic DNS (DDNS) updater service written in Rust. It periodically checks for changes in your public IP address and automatically updates your configured dynamic DNS records.

Designed for simplicity and robustness, it leverages Nix with Home Manager for easy and declarative configuration on NixOS or any system with Nix.

Features

• Multiple Provider Support: Out-of-the-box support for DuckDNS, FreeDNS, and OVH.
• IPv4 and IPv6: Can update records for both A (IPv4) and AAAA (IPv6) records.
• Interface Monitoring: Monitors a specific network interface for IP changes.
• Efficient: Uses an asynchronous (tokio) runtime and only sends updates when your IP address actually changes.
• Persistent State: Remembers the last-sent IP to avoid redundant API calls to your DNS provider.
• Easy Deployment: Comes with a Nix Flake for simple, reproducible setups using Home Manager.
• Configurable Polling: Set a custom polling interval for each DNS record you want to update.

Supported Providers

The service is configured via environment variables. The DNS_TUPLES variable holds the configuration for one or more DNS records. Each record is a semicolon-delimited string, and multiple records are separated by commas.

The general format is: PROVIDER;...

Here are the specific formats for each supported provider:

• DuckDNS: DD;TOKEN;VERSION;POLL_SECS;SUBDOMAIN_NAME

  • TOKEN: Your DuckDNS account token.
  • VERSION: ipv4 or ipv6.
  • POLL_SECS: The interval in seconds to check for an IP change. Set to 0 to check only once on startup.
  • SUBDOMAIN_NAME: The DuckDNS subdomain you want to update (e.g., my-domain).

• FreeDNS: FD;TOKEN;VERSION;POLL_SECS

  • TOKEN: The update token for your FreeDNS record.
  • VERSION: ipv4 or ipv6.
  • POLL_SECS: The interval in seconds to check for an IP change. Set to 0 to check only once on startup.

• OVH: OVH;USERNAME;PASSWORD;SUBDOMAIN;VERSION;POLL_SECS

  • USERNAME: Your DynHost username.
  • PASSWORD: Your DynHost password.
  • SUBDOMAIN: The full subdomain you want to update (e.g., home.example.com).
  • VERSION: ipv4 or ipv6.
  • POLL_SECS: The interval in seconds to check for an IP change. Set to 0 to check only once on startup.

Configuration

The application is configured using two environment variables:

• INTERFACE: The network interface to monitor for IP address changes (e.g., eth0, wlan0).
• DNS_TUPLES: A comma-separated list of DNS provider configurations (see formats above).

Example DNS_TUPLES value:

"DD;ax...1;ipv4;300;my-domain,OVH;user-dyn;pa...ss;home.example.com;ipv6;600"

Usage

With Nix & Home Manager (Recommended)

This project includes a Nix Flake that provides a Home Manager module for easy configuration.

1. Add the flake to your home.nix inputs:

   # home.nix
   {
     inputs = {
       # ... your other inputs
       dns-updater.url = "github:juancabe/dns-updater";
     };
   }

2. Import the module and configure the service:

   # home.nix
   { inputs, pkgs, ... }: {
     imports = [
       # ... your other imports
       inputs.dns-updater.homeManagerModules.default
     ];
   
     services.dns-updater = {
       enable = true;
       interface = "wlan0"; # The network interface to watch
       dnsTuples = [
         # Update my-domain.duckdns.org for IPv4 every 5 minutes
         "DD;your-duckdns-token;ipv4;300;my-domain"
   
         # Update home.example.com at OVH for IPv6 every 10 minutes
         "OVH;your-ovh-username;your-ovh-password;home.example.com;ipv6;600"
   
         # Update a FreeDNS record for IPv4 once at startup
         "FD;your-freedns-token;ipv4;0"
       ];
     };
   }

3. Rebuild your Home Manager configuration:

   home-manager switch --flake .

With Cargo

You can also build and run the service manually using Cargo.

1. Clone the repository:

   git clone https://github.com/your-github-username/dns-updater
   cd dns-updater

2. Set the environment variables:

   export INTERFACE="eth0"
   export DNS_TUPLES="DD;your-token;ipv4;300;your-domain"

3. Run the service:

   cargo run

Nix Flake

The flake.nix provides the following outputs:

• packages.<system>.default: The dns-updater binary, built for the specified system. You can run it directly with nix run github:your-github-username/dns-updater.

• homeManagerModules.default: The Home Manager module for declaratively configuring the service, as shown in the usage guide above. This is the intended way to use the flake.